Vehicles designed for exploration of the planets, satellites and other atmospheric bodies in the Solar System favor the use of mid-L/D (Lift/Drag) lifting blunt body geometries. Such shapes can be designed to yield favorable hypersonic heat transfer and aerothermodynamic properties for low heating and hypersonic aerodynamic properties for maneuverability and stability, coupled with desirable terminal low supersonic/transonic aerodynamics, flexible trajectory design based on long down-range and cross-range performance. This includes precise control of landing site and high delivered payload mass with low packing density to better satisfy mission goals and economics. Entry trajectory selection will influence entry peak heating and integrated heat loads, which in turn will influence selection and design of the vehicle thermal protection system (TPS). Thus, a nominal trajectory must be determined for each shape considered. The vehicle will be subject to both launch and entry loading to meet structural integrity constraints that may further influence shape design. Further, such vehicles must be practical, be sized to fit on existing or realizable launch vehicles, often within existing launch payload-fairing constraints.
Past missions to planets, such as Mars and Venus, and even reentry into Earth have predominantly used a capsule configuration, either with a truncated sphere section, such as the Apollo and Soyuz configurations, or with a sphere-cone design, such as the Viking and Pathfinder series of probes. However, these vehicles are of limited lift and maneuverability and have probably reached the upper limit of their practical payload deliverability. In contrast, high-lift winged vehicles such as NASA's Shuttle Orbiter have proven to be expensive to operate and vulnerable to launch debris as a consequence of their launch configuration.
What is needed is a simultaneous optimization approach that (1) takes account of the atmosphere and environmental characteristics through which the vehicle will move, (2) uses a multi-disciplinary approach to simultaneously optimize structural, aerodynamic, aerothermodynamic, heat transfer and material responses of the vehicle, through choice of geometric parameters and materials associated with the vehicle, and (3) provides a mechanism for comparison of optimal vehicle performances using different approaches.